Hi DH. That is a pure thrust quake. The first quake, which was a M>3.0 was a strike-slip with thrust component. The second quake, which was a M>2.2 was almost a pure thrust quake. The depth is 18Km not 18 miles. This is the depth, which some if not most of the larger quakes occur in California. The fault map I have shows an fault in the area of these quakes, but there is no for it, nor any history. Take Care…Don in creepy town